THIS FIRST SUPPLEMENTAL INDENTURE, dated as of September 17, 2008 (this First
Supplemental Indenture), supplements and amends the Indenture dated as of September 17, 2008 (the Original Indenture) among FRONTIER OIL CORPORATION, a Wyoming corporation, as issuer (the Company), the
GUARANTORS (as defined hereinafter) named therein and WELLS FARGO BANK, NATIONAL ASSOCIATION, a national banking association, as trustee (the Trustee).